The Black-eared marmoset, which is characterised by black tufts of hair around its ears, reaches a size of 19 to 22 cm and weighs up to 350 g.

A broad-spectrum antibiotic was administered in the primates' food to prevent any further cases.

Back into the swing of things. The NZG's Black-eared marmosets are healthy again (Picture: Dr Ian Espie)

NZG and Design Biologix control outbreak of deadly primate disease

Dr Ian Espie, Chief Veterinarian, NZG

One morning in November 2009, four Black-eared marmosets (Callithrix penicillata) in a group of twelve individuals were found dead in their enclosure. The animals ranged from one to five years of age and three were young males.

The carcasses were immediately submitted for post mortem at the NZG's veterinary hospital where Dr Emily Lane, the NZG's Wildlife Pathologist diagnosed yersiniosis from lesions in the intestines and livers. Samples of the affected organs were submitted to the laboratory for bacterial culture and identification as well as anti-biogram.

A few days later, the laboratory confirmed Dr Lane's tentative diagnosis of yersiniosis. The disease, which is very acute especially in small primate species and susceptible animals, usually results in rapid death of the infected animal. Yersiniosis can be treated successfully with broad-spectrum antibiotics.

The organism which causes the disease is Yersinia enterocolitica, a species of bacterium belonging to the family Enterobacteriaceae. It is mainly a disease of animals but can also infect humans. It chiefly affects the digestive tract, liver and spleen. Outbreaks of the disease are usually associated with wet and cold weather. Carrier animals within the group may not show symptoms of the disease, but these animals may provide infectious organisms which can fatally affect young animals which have no immunity and have never been exposed to the disease before.

Once the laboratory confirmed the diagnosis of Yersinia enterocolitica, the remaining animals in the colony were put onto a broad-spectrum antibiotic, administered in their food to prevent any further cases.

A vaccine is developed

For controlling the disease in the NZG's colonies of primates, the bacteriologist at the laboratory suggested that a vaccine could be produced from the bacterial isolate from the NZG's primates. The company Design Biologix in Pretoria was requested to prepare the Yersinia vaccine for the NZG.

Early in January the first dose of the vaccine was administered to the colony of Black-eared marmosets. A booster dose was given one month later. Other primates such as Ruffed lemur (Varecia variegata variegata), Cotton top tamarin (Saguinus oedipus) and Golden lion tamarin (Leontopithecus rosalia), which are also susceptible to Yersinia were subsequently vaccinated as part of the Zoo's preventive medicine programme.

Since the vaccinations there have been a number of occasions at the NZG where there has been extensive wet and cold weather and there have been no further cases of the disease in our animals.

We are grateful to Design Biologix for producing a vaccine for controlling a fatal disease in the NZG's primates.